Everything You Need to Know About the Pfizer Vaccine

doctor putting vaccine into a syringe

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Key Takeaways

  • Pfizer's version of the COVID-19 vaccine was the first to be approved, making its rounds starting mid-December.
  • Under an Emergency Use Authorization, people 12 and older have been approved to get the vaccine.
  • Healthcare workers and residents of long-term care facilities were the first to get the vaccine. Now people in all 50 states are eligible to get the vaccine.
  • Preliminary data shows that the Pfizer vaccine does not appear to have any serious risks for pregnant people, although the self-reported data does not include outcomes from those who were vaccinated during the first trimester of pregnancy.

In mid-December, in the middle of an otherwise bleak month characterized by a precipitous rise in COVID-19 deaths across the country, drug manufacturer Pfizer received emergency authorization to begin distributing their version of a COVID-19 vaccination. 

Here's what you need to know about this COVID-19 immunization option.

All About the Pfizer COVID-19 Vaccine

Approved for people 12 and over, including pregnant and lactating women, the vaccine produced by scientists at Pfizer comes in the form of two injections, given three weeks apart. It is being distributed among all 50 U.S. states. As of May 10, 2021, all individuals above the age of 12 are eligible to take the vaccine.

The COVID-19 vaccine created by Pfizer might be new, but it comes from a wealth of research conducted on other strains of coronaviruses, a class of viruses characterized by spikes that resemble a crown. Other variants of coronaviruses you may be familiar with are SARS and MERS. 

Jason G. Newland, MD, MEd

The Pfizer vaccine was based on studies that were done on previous coronaviruses recognizing that the spike protein is part of the keys to our bodies producing antibodies.

— Jason G. Newland, MD, MEd

According to Jason G. Newland MD, MEd, professor of pediatrics at Washington University’s St. Louis Children’s Hospital, “Previous research has allowed us to understand what parts of the virus are important in its life cycle and for our bodies to make antibodies to prevent us from getting sick. The Pfizer vaccine was based on studies that were done on previous coronaviruses recognizing that the spike protein is part of the keys to our bodies producing antibodies.”

Is the Pfizer Vaccine Safe?

For now, Pfizer’s version of the COVID-19 vaccine remains unapproved by the FDA. But that’s more a matter of timing than safety. The pandemic has forced scientists into a race to create a safe and effective vaccine in a mind-bogglingly short amount of time.

Typical vaccine trials can last for years or even decades, but these vaccines—those created by Pfizer, Moderna, and the ones that have followed—have been pushed out on emergency authorizations. That means they're presumed safe for the general public based on limited clinical trials.

The Pfizer vaccine has been well tested, though, and has been very well-received with few side effects. The FDA's data sheet for the vaccine indicates it’s been tested on roughly 20,000 people in clinical trials and “has been shown to prevent COVID-19 following two doses, given three weeks apart.”

On April 1, Pfizer CEO Albert Bourla communicated that the Pfizer vaccine will likely need to be taken annually, similar to the flu shot. A lot of the logistics depend on how much the COVID variants evolve and spread. Despite that, “vaccine efficacy is 94% to 95%, which is extremely high,” says Newland.

On June 25, 2021, the FDA revised the patient and provider fact sheets for the Pfizer (and Moderna) vaccine to include the suggested increased risks of inflammation of the heart muscle (myocarditis) and inflammation of the tissue surrounding the heart (pericarditis) following vaccination, particularly among adolescents and young adults. Still, the Centers for Disease Control and Prevention (CDC) says the benefits of vaccination outweigh the known and possible risks, including myocarditis and pericarditis.

Side Effects

Side effects of the Pfizer vaccine have been minimal during clinical trials. They include:

  • Pain at the injection site
  • Fatigue
  • Headache
  • Chills
  • Joint pain
  • Muscle pain
  • Fever
  • Injection site swelling or redness
  • Nausea
  • Feeling unwell
  • Swollen lymph nodes (lymphadenopathy) 

Who Should Not Get the Vaccine

You should not get the vaccine if you’ve had an immediate allergic reaction (even if not severe) to any ingredients in an mRNA COVID-19 vaccine or to PEG and polysorbate.

If you have had an immediate allergic reaction to a vaccine or injectable therapy for another disease, talk to your doctor about whether you should receive the vaccine.

The CDC says the vaccine is safe for those with a history of severe allergic reactions, including food, pet, venom, environmental, or latex allergies. However these individuals should be monitored for 30 minutes after receiving the injection.  

Can Pregnant People Get the Pfizer COVID-19 Vaccine?

The uncertainty of the coronavirus pandemic has been difficult for everyone, but perhaps no more so than for pregnant individuals. If you’re pregnant or breastfeeding and you’re considering the Pfizer vaccine, know that the American College of Obstetricians and Gynecologists has issued a statement in support of the shot. The official language says, “ACOG recommends that COVID-19 vaccines should not be withheld from pregnant individuals.”

While the vaccine has been shown to be safe and effective for the general population, it’s important to note that none of the vaccines currently available under the emergency use authorization have been tested in pregnant individuals. That means that there are no safety data to lean on when deciding whether or not to get the COVID-19 vaccine if you’re pregnant or lactating.

A preliminary study of 35,691 people, ages 16 to 54, who were pregnant between December 14, 2020 to February 28, 2021, found that mRNA vaccines, including Pfizer, do not appear to have any serious risks. The incidence of adverse events in the study group, such as preterm birth, was similar to or lower than the incidence of adverse events in the general public. In other words, the study participants weren't any more likely to have pregnancy loss or poor neonatal outcomes than their unvaccinated peers.

The self-reported data was from the CDC's V-safe smartphone-based surveillance system and the CDC's Vaccine Adverse Event Reporting System (VAERS), and did not include any results from people who received a vaccine in the first trimester of pregnancy.

Despite that, it has been shown that pregnant individuals can sometimes have more severe cases of COVID-19 than their nonpregnant counterparts. According to the ACOG statement, “Available data suggest that symptomatic pregnant patients with COVID-19 are at increased risk of more severe illness compared with nonpregnant peers.” If you are pregnant, discuss vaccine risks and benefits with your doctor.

Can Kids Get the Pfizer COVID-19 Vaccine?

Pfizer’s COVID-19 vaccine is approved for kids ages 12 and up. Pfizer has also begun testing on children younger than 12, examining age groups 6 months to 2 years old, 2 to 5 years old, and 5 to 12 years old.

What This Means For You

Health teams continue to work hard to distribute COVID-19 vaccines. It's still important to practice the health measures we know can cut down on the spread of the virus, including frequent hand-washing. People who are not vaccinated should continue to wear masks in public settings.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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